Noninvasive assessment of valve lesions with Doppler ultrasound.

Noninvasive assessment of valvular lesions with Doppler echocardiography is based on determination of velocities of blood flow in the region of cardiac valves, adjacent cardiac chambers and in the large vessels. Obstructions lead to an increase in the velocity of flow in the region of the stenosis which can be registered with the Doppler technique. Through application of the Bernoulli equation, from the maximal velocity, the pressure gradient across the stenotic valve can be calculated. Additionally, the severity of the stenosis is reflected in the temporal course of the velocity curve of the jet through the stenosed valve. For this purpose, in mitral stenosis, the pressure half-time is employed and, in aortic stenosis, the peak of the velocity curve during systole is used. The severity of tricuspid and pulmonic stenosis can also be classified with a method analogous to that used in obstruction of the left heart. The diagnosis of valvular incompetence is based on the detection of regurgitant flow. The extent of regurgitant flow into the proximal cardiac chamber enables semiquantitative classification of severity. The intensity of the jet through the incompetent valve is also indicative of the size of the regurgitant volume. Similar to that in obstructive lesions, the temporal course of the velocity curve is also related to the severity. In association with high-grade regurgitant lesions, there is a premature decrease in the velocity curve. Additionally, the severity of aortic regurgitation can be assessed on the basis of the extent of regurgitant flow in the descending aorta or the subclavian arteries.(ABSTRACT TRUNCATED AT 250 WORDS)